For about forty years, a popular hobby craft activity for both children and adults has been the production of objects from a heat-shrinkable sheet material known by the trademark SHRINKY DINKS, a registered trademark of K & B Innovations, Inc. The material consists of a sheet of thin plastic material that can be colored and/or cut out, and then heated to cause it to shrink and form thickened and hardened art forms. Typically the plastic sheet material is composed of a heat-shrinkable polystyrene base material coated with a water-insoluble, ink-receptive coating. The sheet material and some of its uses are described in U.S. Pat. No. 4,102,456, granted Jul. 25, 1978, and U.S. Pat No. 6,157,865, granted Dec. 5, 2000. Coatings for the base material are described in U.S. Pat. No. 3,889,270 granted Jun. 10, 1975, U.S. Pat. No. 4,503,111 granted Mar. 5, 1985, U.S. Pat. No. 4,555,437 granted Nov. 26, 1985, U.S. Pat. No.5,190,805 granted Mar. 2, 1993 and U.S. Pat. No.5,206,071, granted Apr. 27, 1993. The disclosures of all of the aforementioned United States patents are incorporated by reference.
Although various kinds of apparatus and methods for producing decorative articles from heat-shrinkable sheet material are known, there remains a need for a simple, easy-to-use, and reliable, way to produce three-dimensional articles such as flower-shaped or leaf-shaped pieces can be used as jewelry, or concave butterfly-shaped pieces that can be combined with miniature incandescent bulbs or light-emitting diodes to produce strings of decorative lighting.